fr.vergne.collection.util

Class MapUtils

java.lang.Object

fr.vergne.collection.util.MapUtils

public class MapUtils
extends Object

Method Summary

Methods

Modifier and Type	Method and Description
static <K,V> boolean	equals(Map<K,V> map1, Map<K,V> map2) This method allows to check whether or not two maps have the same content (same keys with same values).
static <T> Map<T,T>	reduceToDirectLinks(Map<T,T> links, boolean keepIntermediaries) This method allows to transform a set of chains A-...
static <K,V> List<V>	translate(List<K> keys, Map<K,V> map, boolean isMissingKeyAllowed) While Map.get(Object) provide the single value assigned to a single key, this method aims at retrieving a List of values corresponding to a List of keys.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

reduceToDirectLinks

public static <T> Map<T,T> reduceToDirectLinks(Map<T,T> links,
                               boolean keepIntermediaries)

This method allows to transform a set of chains A-...-Z to a set of direct links A-Z. The assumption is that each (key, value) entry of the Map gives a direct link, like (A, B), (B, D), (C, D), etc. By aggregating the links we are able to rebuild the chains and find the last elements of these chains. This method produces a Map in which all the values correspond to the final element of the chain that the key is part of.

Parameters:

links - the links to reduce

keepIntermediaries - true if all the keys should be preserved, false if only the keys which are not used as values should be kept

Returns:

the direct links to the final elements of the chains

Throws:

IllegalArgumentException - a loop is present at the end of a chain (we cannot have it elsewhere with a map)

equals

public static <K,V> boolean equals(Map<K,V> map1,
                   Map<K,V> map2)

This method allows to check whether or not two maps have the same content (same keys with same values).

Parameters:

map1 -

map2 -

Returns:

true if they are equals, false otherwise

translate

public static <K,V> List<V> translate(List<K> keys,
                      Map<K,V> map,
                      boolean isMissingKeyAllowed)

While Map.get(Object) provide the single value assigned to a single key, this method aims at retrieving a List of values corresponding to a List of keys.

Parameters:

keys - the keys to consider

map - the translation map

isMissingKeyAllowed - true to map an unknown key to a null value, false to throw an exception

Returns:

the values corresponding to the keys

Throws:

IllegalArgumentException - if a requested key is not found in the map and non-mapped keys are not allowed